The manufacturing industry uses various methods to join materials together. For example, spot welding is typically used to weld sheet metal, wire mesh and other metal parts. In a resistance spot welding process, two electrodes are used to concentrate welding current into a small spot and to simultaneously clamp the work-piece together. Applying a current through the spot will melt the metal and form the weld. Contacting metal surfaces are joined by the heat obtained from resistance to electric current. Spot welding involves three stages: to bring the electrodes into contact with the surface of work-piece and applying a slight amount of pressure, applying the current from the electrodes to the spot, and remaining the electrodes in place to allow the material to cool and solidify.
Another example is a self-piece riveting which is a high-speed mechanical fastening process for point joining similar materials such as sheet material or a material combination. The self-piecing riveting generally uses a semi-tubular rivet to clinch the sheets in a mechanical joint. The process starts by clamping the sheets between the die and the blank holder. The rivet is driven into the sheets to be joined between a punch and die in a press tool by a self-piecing riveting machine. The rivet pierces the top sheet and the die shape causes the rivet to flare within the lower sheet to form a mechanical interlock. Similarly, self-threading/piecing screws or self-threading/piecing bolts processing joins the pieces together at join points. Yet another example is an adhesive gun that applies adhesive to join material together.
The processes described above can be manually performed by an operator using a machine or a gun. The inventor has recognized that locating a join position may become an issue. For example, the operator may work continuously on multiple join positions at pieces and may need to walk along the pieces to be joined (e.g., an assembly line). Consequently, the operator may have difficulty aiming the spot welding gun at the correct positions due to the operator's movement and fatigue from using the heavy machine. As such, repeatability on the join position for work-pieces and quality of the pieces being joined suffer. There exists a need for a joining machine that provides a guide to the operator to locate the join positions in the pieces.